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<head><meta charset="utf-8"><title>build dependencies in alloc crate · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/build.20dependencies.20in.20alloc.20crate.html">build dependencies in alloc crate</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/build%20dependencies%20in%20alloc%20crate/near/220317990" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jake Hughes <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/build.20dependencies.20in.20alloc.20crate.html#220317990">(Dec 17 2020 at 23:29)</a>:</h4>
<p>I have a rust fork where I add an external crate to <code>library/alloc</code>. I'm doing this with the <code>rustc-std-workspace-core</code> hack to get around the dependency chicken-egg problem with the core library. Unfortunately, when I specify <code>[build-dependencies]</code> for my external crate, I get a bunch of scary looking errors when compiling rustc. They look like errors I've seen when you forget to mark things as <code>not(bootstrap)</code>. There are also a bunch of these warnings too:</p>
<p><code>
error[E0658]: auto traits are experimental and possibly buggy
  --&gt; library/core/src/marker.rs:38:1
   |
38 | / pub unsafe auto trait Send {
39 | |     // empty.
40 | | }
   | |_^
   |
   = note: see issue #13231 &lt;https://github.com/rust-lang/rust/issues/13231&gt; for more information
   = help: add </code>#![feature(optin_builtin_traits)]<code> to the crate attributes to enable
</code></p>
<p>I won't list them all because the backtrace is very long, and I have a feeling these are spurious anyway. Is there a magic trick that you use allow  build-dependencies in crates which are extern crates in the compiler?</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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